brushless question?

[the mad1]

i have been away from the rc scene for 14 years and man there has been some changes lol anyway onto the questions
i have just bought a losi xxx-cr and an xray t2 with a speed passion esc and brushless 13.5t and a demon 5000 20c lipo, now i have been told the speedo is limited to a 5.5t but i am unsure on what this sencored and not sencored motors is all about have i made the right decision or should i have gone sencorless

also i do want to find a motor for the summer season something around a 5.5 what motors are worth looking at bare in mind i am running to a tightish budget as i also have 2 kids that are starting racing with me lol